Field of the Invention
The present invention relates to an electronic device having a plurality of sensors used to detect movement of an external detection target, a power control method, and a storage medium storing a program thereof.
Description of the Related Art
A detection system which detects a change in sensing target as a time series using a plurality of sensors is known. For example, two infrared sensors which detect the presence of a heat source such as a person are prepared at points A and B, and detection times of the sensors at the points A and B are overlaid to detect movement of a person as a detection target from the point A to the point B. In this arrangement, as the number and types of sensors are increased, detection can be made at higher precision.
Japanese Patent Laid-Open No. 2012-087962 describes an arrangement which combines a sensor which can detect a broad range at a low resolution, and a sensor which can detect a narrow range at a high resolution. In this arrangement, after an access of a person is detected by the former sensor, an azimuth direction in which the person exists practically is detected using the latter sensor, the azimuth direction in which the person exists can be precisely detected using a small number of sensors.
In general, to a sensor, a power supply line for the sensor and a detection signal line used to notify a CPU or the like of detection are connected. As the number of sensors in a system increases, the number of detection signal lines is also increased, thus consuming I/O ports of the CPU as the notification destination. Also, total power consumption consumed by the sensors in the whole system is also increased. However, even when power supply lines are configured to power only required sensors, these power supply lines further unwantedly consume I/O ports of the CPU.
However, in the power control arrangement required to power only required sensors, the CPU has to always be in an operating state. Therefore, when the power consumption of the CPU is large, electric power which can be reduced by turning off a power source of unnecessary sensors by the power control may be canceled out. Also, even when the power control is configured to be executed via a dedicated IC (integrated circuit) or encoder/decoder in place of the CPU, the detection system is more complicated.